|Ashby, Richard - Rick|
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/2007
Publication Date: N/A
Interpretive Summary: Structured lipids (SLs) are lipids that have been modified to change the natural composition or positions of fatty acids on the glycerol back bone to achieve desired nutritional, physical or chemical properties. A series of SLs were synthesized by incorporating stearic acid, a saturated fat, into canola oil by different methods. One method involved catalysis of the process using an enzyme from Rhizomucor miehei and the other used the chemical sodium methoxide. Different stearic acid and canola oil ratios were used for the study. The SLs produced were purified and the resulting glycerides were identified and characterized. Based on their composition and properties, the structured lipids formed were deemed to be suitable for use in light margarines as an alternative to partially hydrogenated fats, thus, allowing the formulation of margarines with lower negligible trans-fat content.
Technical Abstract: Incorporation of stearic acid into canola oil to produce trans-free structured lipid (SL) as a healthy alternative to partially hydrogenated fats for margarine formulation was investigated. Response surface methodology was used to study the effects of Lipozyme RM IM from Rhizomucor Miehei and Candida rugosa lipase isoform 1 (LIP1) and two acyl donors, stearic acid and ethyl stearate, on the incorporation. Lipozyme RM IM and ethyl stearate gave the best result. Gram quantities of SLs were synthesized using Lipozyme RM IM and the products compared to SL made by chemical catalysis, and fat from commerical margarines. After short-path distillation, the products were characterized by GC and RPHPLC-MS to obtain fatty acid and triacylglycerol profiles, C NMR spectrometry for regiospecific analysis, X-ray diffraction for crystal forms, and DSC for melting profile. Stearic acid was incorporated into canola oil, mainly at the sn-1, 3 positions for lipase reaction and no new trans fatty acids formed. Most SL products did not have adequate solid fat content or B' crystal forms for tub margarine, although these may be suitable for light margarine formulation. Keywords: Candida rugosa lipase isoform 1, Canola oil, Intersterification, Lipozyme RM IM, Response surface methodology, Sodium methoxide, Stearic acid